The Biblical words for “preaching” have the sense of announcing, or heralding – an official proclamation of ambassadors on behalf of a foreign dignitary, or the salutary news of victory from the battlefront. As much as the forgiveness of sins is shorthand for justification, so justification is shorthand for salvation. And Christian preaching, as it should be preaching of the gospel, must substantially involve the preaching of justification.
The familiar words of Isaiah 40:1-2 call to mind the sonorous strains of Handel’s Messiah: “‘Comfort ye, comfort ye my people,’ saith your God. ‘Speak comfortably to Jerusalem, and cry unto her … that her iniquity is pardoned.’” They are also suggestive of the preaching task. In fact, the famous hymn writer, John Newton, preached a series of sermons on the texts of the Messiah to his London parish while Handel’s oratorio was being performed across town. Newton was taking up the charge of Isaiah’s God. As Dr. J. I. Packer explains, comfort “in the old, strong, Bible sense of the word” means to strengthen, encourage, and reassure. That is what the doctrine of justification does when preached from the pulpits – and the live-feeds – of our churches. And how we need comfort and reassurance in these perilous times.
Justification is more than the forgiveness of sins. It is God’s verdict, reckoning Christ’s righteousness to our account, that we are innocent and just. Yet, it is summarily, or by synecdoche (the part for the whole), the forgiveness of sins. The Apostle Paul expresses such, in reliance on the sweet Psalmist of Israel: “David also describeth the blessedness of the man, unto whom God imputeth righteousness without works, saying, ‘Blessed are they whose iniquities are forgiven, and whose sins are covered.’” (Rom 4:5-7, cf. Psa 32:1-2) The forgiveness of sins has always been music to the ears.
The Lord Jesus commanded “that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.” (Luke 24:47) Christ himself announced his commission “to preach the gospel to the poor … the acceptable year of the Lord.” (Luke 4:18-19) This reference from Isaiah alludes to the recurring year of Jubilee, a release of all debts that typified the remission, or canceling, of the crushing debt of sin.
 J. I. Packer, Knowing God (Downers Grove, IL: InterVarsity, 1973), 23.